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Methoxylation of magnesium studied by direct recoil spectroscopy, SIMS and XPS: Calibration of relative surface hydrogen concentration
A225 Surface Science 154 (1985) 315-330 North-Holland, Amsterdam
315
METHOXYLATION OF MAGNESIUM STUDIED BY DIRECT RECOIL SPECTROSCOPY, S I M S AND XPS: C A L I B R A T I O N O F R E L A T I V E SURFACE HYDROGEN CONCENTRATION J. A l b e r t S C H U L T Z , S a l v a t o r e C O N T A R I N I , J. W a y n e R A B A L A I S
Yang-Sun JO and
Department of Chemistry, University of Houston, University Park, Houston, Texas 77004, USA Received 29 May 1984; accepted for publication 15 November 1984 Chemisorption of methanol on polycrystalline magnesium is studied by time-of-flight analysis of directly recoiled (DR) surface atoms, angular resolved X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). The combined measurements show that decomposition occurs to form - 0.14 monolayers of surface hydroxide at methanol exposures < 4 L. High exposures result in molecular chemisorption to form a single methoxide overlayer. The DR results reveal that the C and H of the methyl group are the outermost atoms on the saturated surface. Analysis of DR intensities allows calibration of the relative signals and comparison with calculated recoil cross sections. The methoxide/Mg system provides a standard for surface hydrogen concentrations by the direct recoil technique.
Surface Science 154 (1985) 331-345 North-Holland, Amsterdam WETFING PHENOMENA ON Fe(ll0) I. S E G A *, W . S E L K E
331 I N T H E (3 × 1) P H A S E
** a n d K. B I N D E R
OF A MODEL
FOR H
***
Institut fftr Festk$rperforsehung der Kernforschungsanlage Jf~fich, Postfach 1913, D-5170 J~lich, Fed. Rep. of Germany Received 1 October 1984; accepted for publication 27 November 1984 Interfaces between the three physically distinct, but equivalent domains in the (3 × 1) phase of a lattice gas model for the adsorbate system H / F e ( l l 0 ) and its Ising analog are studied. In the ground state two types of wetting transitions are found where a light or a heavy domain wall decomposes into two heavy or two light walls separated by the third domain. These transitions give rise to wetting lines in the phase diagram which are located using Monte Carlo techniques.
Surface Science 154 (1985) 347-356 North-Holland, Amsterdam INTERACTIONS OF NITRIC OXIDE WITH TEMPERATURES * D a - R e n H E ** a n d F . W . S M I T H
347 Si ( 1 1 1 ) A N D ( 1 0 0 ) A T H I G H
Physics Department, City College of New York, New York, New York 10031, USA Received 13 August 1984; accepted for publication 31 December 1984 The interactions of nitric oxide (NO) with the clean Si (111) and (100) surfaces have been studied at high temperatures (1220-1390°C) for NO pressures between 6 × 10 -6 and 2 × 10 --4 Torr. Growth of silicon nitride has been observed for high NO pressures P(NO) and low substrate
315
METHOXYLATION OF MAGNESIUM STUDIED BY DIRECT RECOIL SPECTROSCOPY, S I M S AND XPS: C A L I B R A T I O N O F R E L A T I V E SURFACE HYDROGEN CONCENTRATION J. A l b e r t S C H U L T Z , S a l v a t o r e C O N T A R I N I , J. W a y n e R A B A L A I S
Yang-Sun JO and
Department of Chemistry, University of Houston, University Park, Houston, Texas 77004, USA Received 29 May 1984; accepted for publication 15 November 1984 Chemisorption of methanol on polycrystalline magnesium is studied by time-of-flight analysis of directly recoiled (DR) surface atoms, angular resolved X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). The combined measurements show that decomposition occurs to form - 0.14 monolayers of surface hydroxide at methanol exposures < 4 L. High exposures result in molecular chemisorption to form a single methoxide overlayer. The DR results reveal that the C and H of the methyl group are the outermost atoms on the saturated surface. Analysis of DR intensities allows calibration of the relative signals and comparison with calculated recoil cross sections. The methoxide/Mg system provides a standard for surface hydrogen concentrations by the direct recoil technique.
Surface Science 154 (1985) 331-345 North-Holland, Amsterdam WETFING PHENOMENA ON Fe(ll0) I. S E G A *, W . S E L K E
331 I N T H E (3 × 1) P H A S E
** a n d K. B I N D E R
OF A MODEL
FOR H
***
Institut fftr Festk$rperforsehung der Kernforschungsanlage Jf~fich, Postfach 1913, D-5170 J~lich, Fed. Rep. of Germany Received 1 October 1984; accepted for publication 27 November 1984 Interfaces between the three physically distinct, but equivalent domains in the (3 × 1) phase of a lattice gas model for the adsorbate system H / F e ( l l 0 ) and its Ising analog are studied. In the ground state two types of wetting transitions are found where a light or a heavy domain wall decomposes into two heavy or two light walls separated by the third domain. These transitions give rise to wetting lines in the phase diagram which are located using Monte Carlo techniques.
Surface Science 154 (1985) 347-356 North-Holland, Amsterdam INTERACTIONS OF NITRIC OXIDE WITH TEMPERATURES * D a - R e n H E ** a n d F . W . S M I T H
347 Si ( 1 1 1 ) A N D ( 1 0 0 ) A T H I G H
Physics Department, City College of New York, New York, New York 10031, USA Received 13 August 1984; accepted for publication 31 December 1984 The interactions of nitric oxide (NO) with the clean Si (111) and (100) surfaces have been studied at high temperatures (1220-1390°C) for NO pressures between 6 × 10 -6 and 2 × 10 --4 Torr. Growth of silicon nitride has been observed for high NO pressures P(NO) and low substrate